Is there a p'sak when dealing with de'os?

Question

I was wondering if the idea of paskening applies to the de'os area of Torah.

As an example there is a machlokes rishonim how to view Chazal's relationship with the science they relied on to pasken on certain issues. Some rishonim say that "nistaneh hatevah" which means that the science they relied on was correct however things have changed (evolved?) since then so our science produces different conclusions. Other rishonim say that they were relying on the science of their time which was a correct thing to do despite the fact that in reality their science was incorrect. Is there an idea to pasken how to view Chazal in this area?

(Just to clarify, I am not asking about de'os that actually have an impact on halacha lema'aseh in terms of how we act.)

Open to all ideas but appreciate sourced ideas the most.

Answer 1

The Rambam writes in his Commentary to the Mishnah to Sotah (3:3):

וכבר אמרתי לך לא פעם שאם נחלקו חכמים באיזה השקפה ודעה שאין תכליתה מעשה מן המעשים הרי אין לומר שם הלכה כפלוני
And I already told you not just once that if our Sages argue on some Haskafah or Deah which has no practical outcome, one does not say in that case, "The Halacha is like X"

and to Sanhedrin (10:3):

כבר הזכרנו לך כמה פעמים שכל מחלוקת שתהיה בין החכמים ואינה תלויה במעשה אלא קביעת סברה בלבד אין מקום לפסוק הלכה כאחד מהם
I have already reminded you a number of times that any argument between Sages which is not connected to [practical] actions but to reasoning alone, there is no place to rule that the Halacha is like one of them

and to Shevu'ot (1:4):

וכבר ביארנו שכל סברא מן הסברות שאין בה מעשה מן המעשים שנחלקו בה חכמים לא נאמר בה הלכה כפלוני.‏
And we already explained that any reasoning which has no application in which our Sages disputed, we do not say regarding it, "The Halacha is like X".

and in his Sefer Hamitzvot (Negative Command 133):

וכבר בארנו בחבורנו בפירוש המשנה שכל מחלוקת שלא תחייב חלוף במעשה אלא בסברא לבד לא אפסוק בו הלכה ולא אומר הלכה כפלוני.‏
And we already explained in our work, the Commentary to the Mishnah, that any argument which does not demand some change in practical application but only in some reasoning, I will not rule regarding it or say, "The Halacha is like X".

Answer 2

In Rambam Kiddush Hachodesh 17:24 he talks about it. In the authoritative version the Rambam writes that:

...., we do not rely on [the personal authority of] the individual who made these statements or taught these concepts, but on the proofs he presented and the reasons he made known.

However this was a controversial statement and when the Rambam was printed they changed it to say "we do rely".

Basically what the Rambam is saying is that if the scientific evidence points a certain way we must pasken that way, and not based on transmitted knowledge without evidence.